Re: kern/43294: locking against myself in ioctl setting up a gre interface

[Andrew Doran <ad%NetBSD.org@localhost>]

The following reply was made to PR kern/43294; it has been noted by GNATS.

From: Andrew Doran <ad%NetBSD.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
        netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/43294: locking against myself in ioctl setting up a gre
        interface
Date: Wed, 12 May 2010 10:04:49 +0000

 > martin
 > this locking panic you ran into
 > someone hammered a locking fix into the socket code without getting it
 +reviewed. if i had time i would back it out, contact the comitter and post it
 +to tech-net.
 > softnet_lock was deliberately NOT taken for interface ioctl operations.
 <martin> andrew: it is now kern/43294, please comment there
 <martin> why wasn't it taken?
 > because interface ioctls do stuff like allocate memory with M_WAITOK and so
 +on.
 > it needs more complex serialization
 <martin> can of worms, I see
 > the fallback position currently is kernel_lock+splnet.
 > but there are still race conditions with that.